Hay Barn, attached Corn Barns, and Pigsty at Lower Dyffryn

The hay barn, attached corn barns, and pigsty at Lower Dyffryn date from the 19th century and are constructed from rubble stone with a slate roof. The west front of the hay barn has a lower end that was originally open-fronted but is now partly filled with blockwork. The wall plate is supported by tall, square stone pillars. To the right, the cowhouse features three large square openings leading to the upper loft, with vertically boarded openings on the left and right. The ground floor has a broad open entry to the byre, and the left wall is weatherboarded with 20th-century infill. The south gable has two tiers of three ventilation slits.

Attached at a right angle to the south gable is the 18th-century corn barn, which is built of uncoursed rubble stone and also has a slate roof. It features large off-centre threshing doorways, of which only one door survives on the south side. A two-bay single-storey pigsty with a gabled slate roof is attached to the west gable of the corn barn. Additionally, on the south side is a 19th-century corn barn made of thinly coursed rubble stone with a hipped corrugated metal roof. The opposing centre doorways to the threshing floor have segmental arches with stone voussoirs, and there are two tiers of two ventilation slits on each of the long walls, as well as three tiers of two slits on the south gable end.

The 19th-century hay barn consists of seven bays and has a fine interior. The roof trusses feature kingposts with angle struts, two tiers of purlins, and a ridge piece. A transverse stone wall separates the lofted cowhouse, which has a square pitching hole and a tall blocked two-light mullion with wooden stanchions, although the right stanchion is missing. The east wall of the hay barn has a stone base with four splayed ventilation slits, above which are horizontal boarded timber-framed panels. The adjoining east wall of the lower cowhouse has three square openings with boarded shutters. The 18th-century barn has four bays and features raking queen strut trusses and two tiers of purlins, while the barn to the south has five bays and 19th-century trusses.